Generally, transmitted radio frequency (RF) is received and transformed to an intermediate frequency (IF) which is then transformed to the actual signal desired, either voice or data. A later advancement led to two components being transmitted for every RF channel—an I component and a Q component. The I and Q components are in quadrature with each other, and therefore do not interfere with each other, thereby allowing greater information transmission than with conventional RF transmission. As a consequence, RF with I and Q components was chosen as the new standard baseband-RF interface for GSM/GPRS/EDGE phones.
GSM is a wireless communication system which relies on time-division multiple access standard for voice. As the demand for wireless data communication increased, GPRS was added to GSM to allow dedicated access to digital data rather than sending data over voice lines as modems and faxes do. Some examples of uses for digital data communications are access to the Internet, access to email and short message service (SMS), and access to multi-media communication. As the need for faster data rates increased, a software based solution called EDGE was introduced for GPRS which allowed data speeds to increase by a factor of more than three over the same frequency spectrum and radio frequency.
Traditionally, an RF module is utilized to convert the received RF frequency to an IF frequency, and another module would convert the IF to a baseband signal. However, some modern communication systems may use an IF of zero Hz. That is, the output of the RF module is a baseband signal. Notwithstanding, this signal is still referred to as IF. Also, other communication systems utilize very low intermediate frequency (VLIF), where the IF frequency is non-zero but lower than the traditional IF of several megahertz, for example, a VLIF frequency of 100 KHz. Some other communication systems may utilize serial digital data of the baseband signal, referred to as digital RF, as output of the RF modules.
As the operating requirements for wireless devices become more demanding, the complexity of the interactions between data processing hardware and RF modules also increases. For example, RF modules from various vendors may be required to work effectively with a baseband processor from a different vendor. The use of individual baseband receiver interfaces for each of the possible RF front-end receivers with which a baseband processor may interface, may prove to be costly in terms of layout space in an integrated circuit. Because component size and cost are critical concerns in wireless devices, the use of multiple baseband receiver interfaces should be limited as much as possible. Moreover, this approach may also limit the number of possible interfaces that may be implemented with a particular baseband processor.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.